This invention is in the field of solar biomass gasification and pyrolysis
As processes, biomass gasification and pyrolysis have been known for a long time. Several different types of reactors have been used to gasify and/or pyrolize biomass including fixed bed reactors, fluidized bed reactors, and entrained flow reactors. A variety of sources of heat for biomass gasification and pyrolysis processes have been used, including fossil fuels (Ni, et al, Fuel Processing Technology, 2006, pp. 461-472) and combustion of biomass or biomass reaction products such as pyrolysis oil (e.g. U.S. Pat. No. 4,497,637 to Purdy et al).
Solar gasification of carbonaceous particles has also been reported in the patent literature. U.S. Pat. No. 5,647,877 to Epstein reports solar energy gasification of solid carbonaceous material in a liquid dispersion. An aqueous dispersion of carbonaceous material is introduced into the reactor so as to form water droplets enclosing particulates of the carbonaceous material. The solid carbonaceous material is heated by solar energy and transfers heat to a surrounding liquid. Hydrogen is produced in the process by the decomposition/gasification of the hydrocarbon (coal) particles. A variety of carbonaceous materials are mentioned as possible feedstocks including coal and various biomasses.
U.S. Pat. No. 4,290,779 to Frosch et al. reports a solar heated fluidized bed gasification system for gasifying carbonaceous material. Solar radiation is introduced into a refractory honeycomb shell which surrounds the fluidized bed reactor. Both coal and organic biomass materials are mentioned as possible powdered carbonaceous feedstocks.
U.S. Pat. No. 4,229,184 to Gregg reports an apparatus for using focused solar radiation to gasify coal and other carbonaceous materials. The solar radiation is directed down through a window onto the surface of a vertically moving bed of the carbonaceous material.
It has been shown that solar thermal reactors can achieve temperatures up to 2500 K (2227° C.). Temperatures even higher than this are achievable, but in those regimes materials and reradiation loss issues become major concerns. Solar thermal systems have been applied to the dissociation of methane (Dahl, et al., International Journal of Hydrogen Energy, 29, 2004) or ZnO (Perkins, et al., International Journal of Hydrogen Energy, 29, 2004; Steinfeld, Solar Energy, 78, 2005). Carbon has been used as reducing agents for ZnO (Müller, R, P Haeberling, and R Palumbo, “Further advances toward the development of a direct heating solar thermal chemical reactor for the thermal dissociation of ZnO(s),” Solar Energy, 80, 2005, pp. 500-511).